The present invention generally relates to magnetic heads for magnetic recording and/or reproducing and more particularly to a composite type magnetic head assembly used in a stationary head type magnetic recording and/or reproducing apparatus such as audio tape recorder or data recorder for recording and/or reproducing an information signal on and from a magnetic tape by a stationary magnetic head carried therein.
Conventionally, there is a magnetic tape recorder such as cassette tape recorder, multi-track tape recorder, data recorder and the like in which a composite type magnetic head assembly is used for recording and/or reproducing an information signal on and from a magnetic tape. The composite type magnetic head assembly comprises a plurality of magnetic heads mounted on a common base body which in turn is mounted on a frame of the tape recorder such that each of the magnetic heads maintains a predetermined relationship with the magnetic tape.
In such a magnetic tape recorder using the composite type magnetic head assembly, it is necessary to adjust the position of the magnetic head such that the offset of the magnetic head in the lateral direction of the magnetic tape as well as the offset of the azimuth angle are eliminated for each of the magnetic heads in the assembly and such that the magnetic heads are properly aligned on the track formed in the magnetic tape. For this purpose, a complex mounting mechanism is used for adjustably mounting the magnetic head assembly on the frame of the tape recorder as is disclosed in the Japanese Laid-open Utility Model Application No. 56-2135. In this mechanism, each of the magnetic heads are mounted adjustably on a common body which in turn is mounted adjustably on the frame.
FIG. 1 shows a principle of azimuth angle adjustment according to a prior art. The view is taken in plane of the magnetic tape which is transported from the left to the right, and shows a first magnetic head H1 which is already adjusted and a second magnetic head H2 which is to be adjusted. The distance between a gap G1 of the magnetic head H1 and a gap G2 of the magnetic head H2 is represented by d. Further, there is provided a fulcrum P1 at the bottom of the magnetic head H2 in the drawing or at the right side of the head H2 when viewed in the tape passing direction and the magnetic head H2 is tilted about the fulcrum P1 in the plane of the paper in the clockwise direction or in the counterclockwise direction. In the drawing, the magnetic head H2 is tilted counterclockwise from an azimuth angle .theta..sub.1 to an azimuth angle .theta..sub.0 for the adjustment. In other words, the azimuth angle .theta..sub.0 represents the azimuth angle which is adjusted properly.
In such an adjustment, the displacement of the magnetic core in the magnetic head H2 associated with the tilting of the head becomes increasingly large with increasing distance from the fulcrum P1. Thus, a displacement d1 of a magnetic core C1 corresponding to a track No.1 closest to the fulcrum P1 is given as d1=A1.sin.theta., a displacement d2 of a magnetic core C2 corresponding to a track No. 2 next closest to the fulcrum P1 is given as d2=A2.sin.theta., and a displacement d3 of a magnetic core C3 corresponding to a track No. 3 which is the farthest from the fulcrum P1 is given as d3=A3.sin.theta., where A1, A2 and A3 are the distance from the fulcrum P1 to the magnetic cores C1-C3 respectively and .theta. represents the difference of angle between the azimuth angle .theta..sub.1 and the azimuth angle .theta..sub.2. Note that there holds a relation A1&lt;A2&lt;A3 and as a result, the displacement d2 becomes larger than the displacement d1 and the displacement d3 becomes larger than any of the displacements d1 and d2 in a same azimuth angle adjustment. In other words, there holds a relation d1&lt;d2&lt;d3.
In such an adjustment of the azimuth angle, therefore, there is a tendency that a minute error in the azimuth angle adjustment causes a large displacement of the magnetic core particularly at the track far from the fulcrum. In order to avoid such an error associated with the adjustment, the manufacturing of the magnetic head has to be controlled strictly. However, such a strict control wastes time and invites increase of the cost of the manufactured magnetic head assembly.
Further, the prior art azimuth angle adjustment described with reference to FIG. 1 requires a complex mechanism using a number of parts which not only invites increase of the cost but also an increase of space to be occupied by the magnetic head assembly. The latter problem is particularly serious in the case of compact portable cassette tape recorder where there is a severe limitation in the space for the magnetic head assembly.